Sound-reproducing device



IN VEN TOR.

ATTORNE H KOCH SOUND REPRODUCING DEVICE Flled June 10 1926 May 1, 1928.

Patented May. 1 1928 UNITED STATES I 1,668,509 PATENT OFFICE.

HENRY KOCH, OF JAMAICA, NEW YORK, ASSIGNOR TO DICTOGRAPH PRODUCTS COR- PORATION, A CORPORATION OF VIRGINIA.

SOUN D-RIEPBODUCIN G DEVICE.

Application filed June 10, 1926. Serial No. 114,888.

This invention relates generally to sound reproducing devices or amplifiers such as are commonly known in the art as loud speakers and more particularly to the actuating unit in such devices.

It is the purpose of this invention to provide means for mounting such a unit so as to minimize the effect of any outside influences, such as microphonic noises and resonant frequencies. It is also the purpose of this invention to provide adjusting means for regulating such a unit to eliminate distortion and cause the unit incombination with the actuated membrane to give a clear and true reproduction.

In order to accomplish these desired results this invention contemplates mounting the unit resiliently and at a distance from the enclosure or cabinet and also variably controllin the movement of the vibratory element of the actuating unit.

The invention will now be described with reference to the drawings which illustrate one embodiment of my invention.

Fig. l is a sectional view of a reproducer embodying this invention;

Fig. 2 is a detail view of the unit and supporting means partly in section;

Fig. 3 is a detail sectional view taken so along lines 33 of Fig. 2;

Fig. at is a detail view partly in section taken along lines 44 of Fig. 3.

Referring more particularly to Fig. 1, the reproducer is illustrated as being enclosed in a cabinet'l having a rear wall 2, end walls 3, top 4 and bottom 5. The amplifier consists of an actuating unit 6 and a two part membrane or diaphragm comprising a sheet having two outwardly curved sections 7 and 8 meeting in a common longitudinal edge 9 where it is attached to the unit. The two sections of the membrane are curved outwardly, from their common edge and are secured at their outer edges to the top and 5 bottom of the cabinet by any suitable releasable means in order that access may be had to the unit 6. I

For the purpose of mounting the unit 6 in a manner to eliminate the effects of shock and resonant frequencies a pair of parallel braces 10, 10 are secured to the ends 3, 3 of the cabinet 1 in spaced relationship to the rear wall 2. A pair of cross arms 11, 11 are attached in parallel relationship to the braces 10, 10 to which the unit 6 is secured or the unit may be secured directly to the braces l0, 10. This affords a mounting for the. unit 6 spaced from all walls of the cabinet. To further insure against disturbing influences the unit 6 is mounted resil- 60 iently upon the cross members 11, 11 by means of elastic washers l3, 14 inserted between the cross members and the unit and also between the heads of the securing screws 12 and the unit 6. The actuating unit or sound reproducer consists essentially of a base 15 upon which is mounted a magnet 16, a pair of electromagnets 17, 17 and a vibratory reed 18. A spindle 19 is attached substantially at the 7 center of the reed l8 and the entire assembly is protected with a dust cover 20, through which the spindle projects, and which is held in place by screws 21. A resilient washer 22 is placed on the spindle 7 where it projects through the cover to further reduce any microphonic noises and to keep out dust.

The vibrating reed 18 is resiliently secured at one end by two screws having threaded engagement with the base 15 and projecting through a felt'Washer 24 placed between reed l8 and the base. The reed extends across the center of the unit and the electromagnets l7 and has its other end 5 free so that upon energization of the electromagnets 17 the reed will be caused to vibrate. At substantially the center of the reed is attached the spindle 19 to which is secured the membrane 7, 8 which will vibrate with the reed due to its attachment thereto.

In order to control the tonal quality and volume the free end of the reed 18 is allowed to vibrate only through a definite amplitude which is manually varied at will. In order to accomplish this control the base 15 is bored to permit rotatable passage of a rod 25 which has upon its inner end a cam or eccentric 26. This cam engages with a plunger 27 which in turn contacts with the 10 under side of reed 18 thereby restricting the motion of the reed in one direction. To restrict the motion in the other direction there is provided a double leaf spring comprising an upper leaf 29 and a lower leaf 28 (Fig. 4) bearing upon the reed to maintain it in contact with the plunger 27. From the foregoing it can readily be seen that by rotating rod 25 the amplitude of oscillation of reed 18 may the varied at will by no siliently mounting said unit free from all sides of said enclosure comprising two brace members secured to opposite sides of said enclosure, a pair of cross members attached to said braces and resilient securing means for fastening said unit to said cross members. v

2. A reproducer including a membrane and a unit attached thereto, said unit com: prising a base, a reed and electromagnets Lecasosi mounted upon said base, a shaft having an eccentric portion journa'led in said base, a plunger contacting with said portion and bearing against said reed to position said reed relatively to said magnets and a spring contacting with the opposite side of said reed adapted to maintain said reed and said plunger in contacting relationship.

3. A reproducer including a membrane, an actuating unit attached to said membrane, an enclosure for said unit, means for resiliently mounting said unit free from all sides of said enclosure, said means including a member secured to said enclosure and extending inwardly thereinto free from all sides thereof, and means for resiliently se curing said unit to said member at a point free from the sides of said enclosure.

In witness whereof, I hereunto subscribe my signature.

HENRY KOCH. 

